1. Field of the Invention
This invention relates generally to a connector for connecting an electric ribbon wire comprising conductors having a round cross-section. Particularly, this invention is drawn to a connector having a smooth, flat, plate-like end portion, an edge of the end portion forming a contact surface, the end portion being bent toward both lateral sides of the connector.
2. Related Art
Electric tape or ribbon wire, in which conductors are often made very thin and are often arranged at a very small pitch, have been used as the internal wiring in household appliances such as VCRs, video cameras, office automation devices, and the like. This ribbon wire comprises electrical conductors, each comprising twisted wire elements, flat conductors, or single wire conductors having a round cross-section (hereinafter referred to as "round conductors"). A suitable ribbon wire is selected and used in accordance with an intended application.
For example, in the electric ribbon wire 4 shown in FIG. 7, a plurality of round conductors 41 each have a diameter d of 0.12 mm. The conductors 41 are arranged in a parallel relation at a pitch D of 0.8 mm. The conductors 41 are covered at their opposite sides by a flexible insulating sheath 42 to provide a ribbon-like, one-piece construction. The insulating sheath 42 is removed from one side of one end of the ribbon wire to expose a portion 43 of the conductors 41. This exposes the side surfaces of the conductors 41. The exposed portion 43 is inserted into a connector which collectively connects the plurality of conductors arranged at the narrow pitch D to a plurality of electrical connection elements arranged within the housing 1.
One conventional electrical connection element (not shown) is disclosed in Japanese Utility Model Unexamined Publication No. 3-46976, in which one end portion of the plate-like element, which has a width corresponding to the pitch of conductors, is bent at an acute angle. The end portion is resilient and acts as a leaf spring. This end portion is urged into contact with the conductor inserted into the housing.
FIG. 8 shows an electrical connection element 51 disclosed in Japanese Patent Unexamined Publication No. 61-131382. The connection element 51 is formed by stamping a plate material, and has an end edge surface (i.e., the surface in the direction of the thickness of the plate) which acts as a contact surface 56. This electrical connection element 51 includes a pair of generally parallel, opposed arms 52 and 53, which are formed into a U-shape. The exposed front end portion of the ribbon wire 4 is inserted into the space between the two arms 52 and 53. A prong 55 of a retainer 54 is used to force the contact surface 56 of the arm 53 into contact with the exposed portion 43 of the conductor 41.
However, with respect to the first above-mentioned conventional electrical connection elements, the pitch D of the conductors is approximately 0.8 mm. Therefore, it is very difficult to produce the leaf spring corresponding to this narrow pitch. Additionally, this electrical connection element is normally not used with a single round conductor. It is possible that the round conductor may be severed by a distal edge of the electrical connection element. Thus, this first conventional electrical connection element has been limited to twisted wire element applications, and has not been suitable for a ribbon wire having round conductors.
The second above-mentioned electrical connection element can be used with a ribbon wire having round conductors. However, since the narrow contact surface 56 must be brought into contact with the thin conductor along its length, the contact surface 56 must be accurately aligned with the exposed conductor. Therefore, if there is a slight manufacturing or assembling error, or if the exposed conductor is bent to the right or to the left, even slightly, the conductor 41 is offset from the electrical connection element 51, as shown in FIG. 9.
As a result, a stable contact cannot be obtained. In the worst case, a contact failure occurs. This can be avoided by making the electrical connection element from a plate having a greater thickness, as shown in FIG. 9, so that the contact surface 56 has a larger width. With this arrangement, however, each connection element-receiving slot of the housing for receiving the electrical connection element 51 must be increased in width. In other words, partition walls of the housing must be reduced in thickness. This makes molding the housing difficult. This also makes it difficult to manufacture the housing having sufficient strength.